code: def get_mask_volume(mask_img):
      """Compute the volume of a brain mask in mm^3.
  
      Parameters
      ----------
      mask_img : nibabel image object
          Input image whose voxel dimensions are to be computed.
  
      Returns
      -------
      vol : float
          The computed volume.
  
      """
      affine = mask_img.affine
      prod_vox_dims = 1.0 * np.abs(np.linalg.det(affine[:3, :3]))
      return prod_vox_dims * _get_data(mask_img).astype(bool).sum()
  
file_path: nilearn/nilearn/_utils/param_validation.py
imports: import numbers
  import warnings
  import numpy
  from sklearn.feature_selection import SelectPercentile, f_classif, f_regression
  from .niimg import _get_data
label_desc: Use image node_id 2 for calling a global function with example usage: get_mask_volume(mask_img) and returns: unknown